Scientists and engineers continue to make improvements in the ways images are scanned and/or stored in digital format. Generally, image-description information is stored in structured fields that collectively are described as the image's header. The image's header are stored in an image's file in addition to the image's pixel values. For example, the TIFF file format produced and trademarked by Aldus Corporation, (411 First Ave. South, Seattle, Wash.), defines many such structured fields.
There are continually developing image editing packages which are employed to use and perform various processing tasks to the stored image files. Because of the large number of possible structured fields, many image-editing packages recognize only a fraction of the fields defined. A result of the lack of recognition of some fields, is that the information stored in these unrecognized fields is often lost. Thus, following the completion of the processing task performed by the editing package, the image file is reformed in processed files that lack the fields that are not recognized. For example, a very popular editing package, Adobe PhotoShop, (sold by Adobe Systems Incorporated, 1585 Charleston Rd., Mountain View, Calif.) deletes the image-description information and the color interpretation of the image's pixel values.
It should be apparent that the removal of the image- description information often degrades the value and quality of the reformed image. Furthermore, it can impede the operation of subsequent image processes and/or systems that would otherwise use this removed information in their operation. Generally the lost information include information that would ordinarily serve various purposes. For example, metadata (a totality of image textural catalog information) that describes an image's content may be stored in an image's header for subsequent use in indexing the image in a database. The removal of a part or all of the metadata may render the file not to be able to be indexed by an image system at some later time.
In order to better understand the present invention, the invention is described in regard to a particular imaging format. The format described is the TIFF format having the following tags definitions:
ImageWidth (100 hex) - width of the image in pixels. ImageLength (101 hex) - length of the image in pixels. BitPerSample (102 hex) - number of bits per color plane. Orientation (112 hex) - The correct orientation with respect to rows and columns of the data. SamplesPerPixel (115 hex) - number of color planes. ImageDescription (10E hex) - ASCII field that describe the content. StripOffsets (111 hex) - the length of the header and where the data starts in the file. TransferFunction (12D hex) - A lookup table to convert the data. DateTime (132 hex) - the time stamp when file is created WhitePoint (13E hex) - the chromaticities of the white point. PrimaryChromaticities (13F hex) - the chromaticities of the color. Copyright (8298 hex) - ASCII field of the copyright message.
Tables 1 and 2, show a structure of the TIFF files at each stage of the process before the present invention. It is noted that the tags listed are not an exhaustive list of tags that a TIFF file may have. The group of tags is selected only to show one particular utilization. Table 1 shows an example of a header and data for an original image file with the structured fields/tags before the file is edited by PhotoShop.
TABLE 1 Original Scanned File Structure: Header: Width tag Length tag BitPerSample tag SamplesPerPixel tag Orientation tag Offset tag Description tag TransferFunction tag DateTime tag WhitePoint tag PrimaryChromaticities tag Copyright tag Data: (bytes of image data) XXXXXXXXX XXX XXXXX
Table 2 shows an example of a modified file structure of fields/tags after the image file is edited by PhotoShop. It is noted that Table 2 no longer has tags for ImageDescription, TransferFunction, DateTime, WhitePoint, PrimaryChromaticities or Copyright. All information in these tags is lost for subsequent image files for all further processing an/or viewing.
TABLE 2 Modified File Structure: (Example: After editing image with PhotoShop) Header: New Width tag New Length tag BitPerSample tag SamplesPerPixel tag Orientation tag new Offset tag Data: (bytes of image data) YYYY YY YYYYYY YYYY